Can Trump cut off funds for sanctuary cities? The Constitution says yes.

But whatever one thinks about Trump’s strategy, it almost certainly would pass muster at the Supreme Court.Several cities and public universities have vowed to resist President-elect Donald Trump’s plan to deport undocumented criminals by doubling down on sanctuary policies. In response, Trump has pledged to curtail federal funding for sanctuary providers. Activists, predictably, are crying foul, and some legal scholars, such as Harvard’s Noah Feldman, have even claimed that such a response would be unconstitutional.

Feldman and others point to New York v. United States (1992) and Printz v. United States (1997), in which the Supreme Court concluded that the federal government cannot conscript state or local officials to carry out federal law. The federal government must enforce its own laws, using federal personnel. So when state or local police arrest immigrants who are present in the country illegally, they are under no obligation to deport them, as deportation is the responsibility of the federal government alone.

This “anti-commandeering” doctrine, however, doesn’t protect sanctuary cities or public universities — because it doesn’t apply when Congress merely requests information. For example, in Reno v. Condon (2000), the Court unanimously rejected an anti-commandeering challenge to the Driver’s Privacy Protection Act, which required states under certain circumstances to disclose some personal details about license holders. The court concluded that, because the DPPA requested information and “did not require state officials to assist in the enforcement of federal statutes,” it was consistent with the New York and Printz cases.

It follows that, consistent with the anti-commandeering doctrine, Congress can require state, local or university police to tell federal agents when they arrest an immigrant present in the country illegally.

It’s true that cities such as Los Angeles instruct city employees not to ask about immigration status, but they may still have access to that information. Under California law, for example, driver’s licenses issued to immigrants in the country illegally contain prominent distinguishing language stating, “federal limits apply.” Indeed, Congress could specify that licenses issued to immigrants in the country illegally must include a distinguishing feature, or they won’t be accepted for federal purposes, such as TSA airport security. Congress already has enacted the Real ID Act, which mandates that driver’s licenses display certain details.

A separate constitutional doctrine, the anti-coercion doctrine, likewise won’t shield sanctuaries. This doctrine holds that while Congress may impose conditions on receipt of federal funds, it cannot coerce states into accepting those conditions.

In the 1980s, Congress passed a law withholding 5% of highway funds from any state that refused to adopt a minimum drinking age of 21. The Supreme Court, in South Dakota v. Dole (1987), upheld it. Because highway funds are expended — in part — to ensure safe travel, the court reasoned that raising the drinking age was “relevant to the federal interest in the project and the overall objectives thereof.” More significantly, withholding 5% of federal funds wasn’t coercive because while it represented a loss of $615 million dollars, it was only 0.19% of states’ total budgets.

By contrast, in NFIB v. Sebelius (2012), the Supreme Court found that Congress violated the anti-coercion doctrine. Specifically, in the Affordable Care Act, Congress withheld 100% of states’ Medicaid funding if they didn’t expand those programs. A court plurality characterized this as a coercive “gun to the head” because it involved a loss of over $233 billion dollars — more than 20% of states’ budgets.

The South Dakota and NFIB cases teach that Congress can cut off funds if the conditions imposed are relevant “to the federal interest in the project” and the threatened loss of money doesn’t amount to a “gun to the head,” defined by a substantial percentage — approaching approximately 20% — of states’ budgets.

Congress certainly could meet these standards. Many federal programs provide billions to universities and state and local law enforcement. Provided the percentage withheld didn’t approach the 20% threshold, it should be constitutional. As with the highway funds in South Dakota, these programs are designed in part to improve safety of campuses and communities. This goal would be furthered by withholding funds from cities and universities that provide sanctuary for criminals present in the country illegally. Such individuals, by definition, not only are unvetted by the federal government, but have committed crimes while here.

Whatever one’s view of the best immigration policy, it should be uniform. Some, including the Washington Post’s editorial board, have suggested that Congress should give sanctuary cities flexibility to report only those who’ve committed the most serious violent offenses. But precisely which criminals should be subject to deportation requires resolution by Congress, not each city or university.

Sanctuary policies create Balkanization on an issue with important foreign policy implications and corresponding potential for diplomatic embarrassment. As the Supreme Court affirmed in Arizona v. United States (2012), “the removal process is entrusted to the discretion of the Federal Government” because it “touch[es] on foreign relations and must be made with one voice.”

The Constitution is clear that power to determine deportation policies belongs to Congress, not states, municipalities or universities.

David Rivkin and Elizabeth Price Foley practice appellate and constitutional law in Washington, D.C. Rivkin served at the Department of Justice and the White House Counsel’s office during the Reagan and George H.W. Bush administrations. Foley is also a professor of constitutional law at Florida International University College of Law.